Problem trying to run Typo edge

Hi all,
When I download the latest trunk of Typo, do I also need to download
a new version of the webserver or something? I get this when I try to
run Typo:

** warning: web-server unknown. Use ‘web-server=external’ to
disable.
/usr/local/lib/ruby/gems/1.8/gems/rails-app-installer-0.2.0/lib/rails-
installer.rb:243:in start': undefined methodstart’ for
nil:NilClass (NoMethodError)
from /usr/local/lib/ruby/gems/1.8/gems/rails-app-
installer-0.2.0/lib/rails-installer/commands.rb:135:in command' from /usr/local/lib/ruby/gems/1.8/gems/rails-app- installer-0.2.0/lib/rails-installer.rb:646:inexecute_command’
from /usr/local/lib/ruby/gems/1.8/gems/typo-4.1.1/bin/typo:38
from /usr/local/bin/typo:16:in `load’
from /usr/local/bin/typo:16